Superconducting magnet device and magnetic resonance imaging apparatus

Abstract

To provide a structure to cancel out a deformation amount applied to a load support due to thermal deformation of a superconducting coil housed in a vacuum vessel in a superconducting magnet device.SOLUTION: A superconducting magnet device of an embodiment includes the vacuum vessel, the superconducting coil, and the insulating load support. The insulating load support supports the superconducting coil through a thermal deformation cancellation mechanism that generates a second deformation amount in a direction of canceling out a first deformation amount applied to the insulating load support by the superconducting coil due to thermal deformation occurring in the superconducting coil when the inside of the vacuum vessel is cooled to an extremely low temperature. The thermal deformation cancellation mechanism includes a thermal deformation member. The thermal deformation member is formed from at least a material having a second coefficient of thermal expansion determined on the basis of a first coefficient of thermal expansion of a material forming the superconducting coil, and generates the second deformation amount by thermally deforming in a same environment as the superconducting coil.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] FIELD OF THE DISCLOSURE The present invention relates to a superconducting magnet device and a magnetic resonance imaging device. [Background technology]

[0002] Conventionally, magnetic resonance imaging (MRI) devices have been used as medical imaging diagnostic devices that perform image-based diagnosis. Magnetic resonance imaging devices (hereinafter referred to as "MRI devices") are devices that capture cross-sectional images of a subject by receiving MR signals excited by RF (Radio Frequency) pulses irradiated in a strong magnetic field using an RF coil.

[0003] MRI devices use superconducting magnet devices that are composed of superconducting coils that generate a strong magnetic field. The superconducting coils that compose the superconducting magnet devices must be used in an extremely low temperature environment. For this reason, in the superconducting magnet devices used in MRI devices, for example, the superconducting coils are housed in a vacuum vessel, and are configured to minimize the intrusion of heat from the outside of the vacuum vessel, which is at room temperature, to the superconducting coil side. Furthermore, some superconducting magnet devices are configured such that the superconducting coils are housed in a radiation shield and housed in the vacuum vessel in this state. In the vacuum vessel or radiation shield, the superconducting coils or radiation shield are supported by load support materials such as rods or cylinders made of fiber reinforced plastics (FRP).

[0004] However, when the superconducting coil housed in the vacuum vessel and the radiation shield in which the superconducting coil is housed are cooled to an extremely low temperature, thermal deformation occurs in the outer shape, although it is slight. For example, the metal material forming the superconducting coil and the radiation shield shrinks due to thermal contraction and expands due to thermal expansion. In this case, in the superconducting magnet device, a load is applied in the bending direction to the load support material supporting the superconducting coil and the radiation shield in the vacuum vessel. Then, in the superconducting magnet device, a positional deviation that is difficult to predict occurs in the superconducting coil due to the thermal deformation (thermal contraction and thermal expansion) of the superconducting coil and the radiation shield and the reaction force against the load in the bending direction of the load support material. This positional deviation of the superconducting coil can be a factor in deterioration of the image quality of a tomographic image of a subject captured by an MRI device. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2000-133850 A Summary of the Invention [Problem to be solved by the invention]

[0006] The problem to be solved by the embodiments disclosed in this specification and the drawings is to provide a structure for offsetting the amount of deformation applied to a load support member due to thermal deformation of a superconducting coil housed in a vacuum vessel in a superconducting magnet device. However, the problem to be solved by the embodiments disclosed in this specification and the drawings is not limited to the above problem. Problems corresponding to the effects of each configuration shown in the embodiments described later can also be positioned as other problems. [Means for solving the problem]

[0007] A superconducting magnet apparatus according to an embodiment is a superconducting magnet apparatus in which at least a superconducting coil is accommodated in a vacuum vessel in a state in which the superconducting coil is supported by a thermally insulated load support, and includes the vacuum vessel, the superconducting coil, and the thermally insulated load support. The thermally insulated load support supports the superconducting coil via a thermal deformation canceling mechanism that generates a second deformation amount in a direction that cancels a first deformation amount applied from the superconducting coil to the thermally insulated load support due to thermal deformation generated in the superconducting coil when the inside of the vacuum vessel is cooled to an extremely low temperature. The thermal deformation canceling mechanism includes a thermal deformation member. The thermal deformation member is formed of at least a material having a second thermal expansion coefficient determined based on a first thermal expansion coefficient of a material forming the superconducting coil, and generates the second deformation amount by thermally deforming in the same environment as the superconducting coil. [Brief description of the drawings]

[0008] [Figure 1] 1 is a diagram showing an example of the configuration of a magnetic resonance imaging apparatus using a superconducting magnet device according to an embodiment; [Diagram 2] FIG. 1 is a diagram showing an example of the configuration of a superconducting magnet apparatus according to a first embodiment. [Diagram 3] FIG. 2 is a diagram showing an example (part 1) of the structure of a thermal deformation cancellation mechanism that supports a superconducting coil in the superconducting magnet device according to the first embodiment. [Figure 4] FIG. 4 is a diagram showing an example (part 2) of the structure of a thermal deformation cancellation mechanism that supports a superconducting coil in the superconducting magnet device according to the first embodiment. [Diagram 5] FIG. 4 is a diagram showing an example (part 3) of the structure of a thermal deformation cancellation mechanism that supports a superconducting coil in the superconducting magnet device according to the first embodiment. [Figure 6] FIG. 11 is a diagram showing an example of the configuration of a superconducting magnet apparatus according to a second embodiment. [Figure 7] FIG. 11 is a diagram showing an example of the structure of a thermal deformation cancellation mechanism that supports a superconducting coil in a superconducting magnet apparatus according to a second embodiment. [Figure 8] FIG. 2 is a diagram showing an example of a configuration for supporting a superconducting coil in a superconducting magnet apparatus according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, a superconducting magnet device and a magnetic resonance imaging device according to embodiments will be described with reference to the drawings.

[0010] A magnetic resonance imaging (MRI) device (hereinafter referred to as an "MRI device") is a medical imaging diagnostic device that irradiates a subject (e.g., a human body) with a radio frequency (RF) pulse while applying a strong magnetic field to the subject, receives electromagnetic waves generated from hydrogen nuclei in the subject's body by the nuclear magnetic resonance phenomenon with an RF coil, and reconstructs a nuclear magnetic resonance signal (hereinafter referred to as an "MR signal") based on the received electromagnetic waves to capture a tomographic image (hereinafter referred to as an "MR image") of the subject. The MRI device can also capture an MR image of the subject by reconstructing the MR signal based on the electromagnetic waves received by an RF coil attached to the subject. The MRI device displays the MR image of the subject, allowing the person performing the MRI examination (such as a doctor or technician) to visually check whether or not the subject has a lesion.

[0011] 1 is a diagram showing an example of the configuration of a magnetic resonance imaging apparatus (MRI apparatus) using a superconducting magnet apparatus according to an embodiment. The MRI apparatus 1 includes, for example, a gantry apparatus 10, a bed apparatus 20, a control device 30, and a console apparatus 40. In this embodiment, the control device 30 and the console apparatus 40 are described as being separate from the gantry apparatus 10, but the gantry apparatus 10 may include some or all of the components of the control device 30 and the console apparatus 40. The MRI apparatus 1 is an example of a "magnetic resonance imaging apparatus."

[0012] The gantry device 10 includes, for example, a static magnetic field magnet 12, a gradient magnetic field coil 14, and an RF coil 16. The gantry device 10 further includes, as a part of the RF coil 16, an RF coil 18 that can be attached to the subject P.

[0013] The static magnetic field magnet 12 is a superconducting magnet device formed in a hollow, approximately cylindrical shape. The static magnetic field magnet 12 generates a uniform, strong static magnetic field in the internal space. The static magnetic field magnet 12 has a superconducting coil housed in a vacuum container. In the static magnetic field magnet 12, the superconducting coil may be housed in a vacuum container in a state where it is housed in a radiation shield. The superconducting coil receives power from the static magnetic field power supply 32 and generates a strong static magnetic field in the imaging space (i.e., in the bore) of the MRI device 1 in which the subject P is introduced. A detailed configuration of the static magnetic field magnet 12 will be described later. In this embodiment, the central axis of the gantry device 10 or the longitudinal direction of the top board 24 of the bed device 20 is defined as the Y-axis direction, an axis perpendicular to the Y-axis direction and horizontal to the floor surface of the room in which the MRI device 1 is installed is defined as the X-axis direction, and a direction perpendicular to the Y-axis direction and perpendicular to the floor surface is defined as the Z-axis direction. In this embodiment, the Y-axis direction is the same direction as the static magnetic field. The static magnetic field magnet 12 is an example of a "superconducting magnet device."

[0014] The gradient magnetic field coil 14 is a coil formed in a hollow, approximately cylindrical shape. The gradient magnetic field coil 14 is disposed inside the static magnetic field magnet 12. The gradient magnetic field coil 14 is formed by combining three coils corresponding to the mutually orthogonal X-axis, Y-axis, and Z-axis. Each of the three coils corresponding to the directions of the axes receives a current individually from the gradient magnetic field power supply 33, and generates a gradient magnetic field in the bore, whose magnetic field strength changes along each of the X-axis, Y-axis, and Z-axis.

[0015] The RF coil 16 is a whole-body coil that is housed in the gantry device 10 and configured to surround the subject P in the imaging space. The RF coil 16 receives RF pulses from the transmission circuit 34 to generate a high-frequency magnetic field and receives an MR signal emitted from the subject P under the influence of the high-frequency magnetic field. The RF coil 16 outputs the received MR signal to the reception circuit 35.

[0016] The RF coil 18 is a local coil attached to the subject P. The RF coil 18 is available in various shapes for each part of the subject P to be imaged (hereinafter referred to as "imaging part"). FIG. 1 shows an example of the RF coil 18 attached to the torso of the subject P. The RF coil 18 receives an MR signal emitted from the subject P due to the influence of the high frequency magnetic field generated by the RF coil 16, and outputs the received MR signal to the receiving circuit 35. The RF coil 18 outputs the received MR signal to the receiving circuit 35 via a coil cable 18c connected to a coil port 26 arranged on the top board 24.

[0017] The bed device 20 is a device that introduces the subject P, who is to be imaged, into the inside of the gantry device 10, i.e., into the bore of the gantry device 10, by moving a top board 24 on which the subject P is placed. In other words, the bed device 20 is a device that moves the top board 24 so that the imaging part of the subject P is at a position suitable for imaging within the cavity of the static magnetic field magnet 12, the gradient magnetic field coil 14, and the RF coil 16, i.e., the magnetic field generated within the imaging port. The bed device 20 includes, for example, a base 22 and a top board 24.

[0018] The base 22 moves the top board 24, on which the subject P is placed, in the horizontal direction (X-axis direction and Y-axis direction) or the vertical direction (Z-axis direction) by the operation of a bed driving device (not shown) which operates in response to a control signal output by the bed control circuit 36.

[0019] The top board 24 is a plate-shaped member on which the subject P is placed. Coil ports 26 to which the coil cables 18c of the RF coil 18 attached to the subject P are connected are arranged on the top board 24. The coil ports 26 are arranged on the top board 24, for example, at the four corners.

[0020] The control device 30 controls the operations of the gantry device 10 and the bed device 20 in response to control from the console device 40. The control device 30 includes, for example, a sequence control circuit 31, a static magnetic field power supply 32, a gradient magnetic field power supply 33, a transmission circuit 34, a reception circuit 35, and a bed control circuit 36. The control device 30 may be provided in the gantry device 10 or in the console device 40.

[0021] The sequence control circuit 31 is a sequencer that performs imaging of the subject P by driving the static magnetic field power supply 32, the gradient magnetic field power supply 33, the transmission circuitry 34, and the reception circuitry 35 based on sequence information set by the console device 40. The sequence control circuit 31 may be, for example, a processing circuit having a processor such as a CPU (Central Processing Unit). The sequence information is information that defines in advance a procedure for performing imaging processing to image the subject P in the MRI apparatus 1. The sequence information indicates, for example, the operations of the static magnetic field power supply 32, the gradient magnetic field power supply 33, the transmission circuitry 34, and the reception circuitry 35 when imaging the subject P and the operation timings thereof (hereinafter referred to as "events") in chronological order. More specifically, the sequence information indicates, as events, the strength and timing of the power (voltage) supplied by the static magnetic field power supply 32 to the static magnetic field magnet 12, the magnitude of the current supplied by the gradient magnetic field power supply 33 to the gradient magnetic field coil 14 and the timing of the current supply, the strength of the RF pulse transmitted (supplied) by the transmitting circuit 34 to the RF coil 16 and the timing of the RF pulse supply, and the timing of the receiving circuit 35 receiving (detecting) the MR signals output by the RF coil 16 and the RF coil 18. The sequence control circuit 31 drives the static magnetic field power supply 32, the gradient magnetic field power supply 33, the transmission circuit 34, and the reception circuit 35 by sequentially executing events indicated in the sequence information at a timing based on a predetermined clock signal, and when the reception circuit 35 receives an MR signal, it transfers the received MR signal (more specifically, data representing the MR signal received by the reception circuit 35 (hereinafter referred to as "MR data")) to the console device 40. The clock signal is generated, for example, by a clock generating circuit not shown including a clock oscillator, and represents a timing used as a reference for the operation of imaging the subject P in the MRI apparatus 1. The clock signal is supplied to each of the components of the control device 30. The sequence control circuit 31 sequentially executes events at a timing based on the clock signal, so that the static magnetic field power supply 32, the gradient magnetic field power supply 33, the transmission circuit 34, and the reception circuit 35 each operate synchronously.

[0022] The sequence control circuit 31 is an example of a "control unit."

[0023] The static magnetic field power supply 32 supplies power (voltage) to the superconducting coil housed in a vacuum vessel in the static magnetic field magnet 12 to generate a static magnetic field.

[0024] The gradient magnetic field power supply 33 supplies current individually to each of the three coils in the gradient magnetic field coil 14, which correspond to the directions of the respective axes.

[0025] The transmission circuitry 34 supplies an RF pulse to the RF coil 16. The RF pulse supplied by the transmission circuitry 34 to the RF coil 16 is a pulse corresponding to a Larmor frequency determined by the type of atomic nucleus of interest and the strength of the magnetic field.

[0026] The receiving circuit 35 detects the MR signals output by the RF coil 16 and the RF coil 18, and generates MR data representing the detected MR signals. The receiving circuit 35 generates the MR data, for example, by converting the MR signals into digital data. The receiving circuit 35 outputs the generated MR data to the sequence control circuit 31. The sequence control circuit 31 transfers the MR data output by the receiving circuit 35 to the console device 40.

[0027] The bed control circuit 36 ​​outputs a control signal for moving the base 22 and the top board 24 on which the subject P is placed to a bed driving device (not shown) provided in the bed device 20 in response to control from the console device 40.

[0028] The console device 40 controls the entire MRI apparatus 1 and collects MR data. The console device 40 includes, for example, a memory 41, a display 42, an input interface 43, and a processing circuit 50.

[0029] The memory 41 is realized by, for example, a semiconductor memory element such as a ROM (Read Only Memory), a RAM (Random Access Memory), a flash memory, a hard disk drive (HDD), an optical disk, etc. The memory 41 stores data such as the MR data output by the sequence control circuit 31 and a reconstructed image (MR image) generated based on the MR data.

[0030] The display 42 displays various types of information. For example, the display 42 displays images generated by the processing circuit 50, GUI (Graphical User Interface) images that accept various operations by the person performing the MRI examination, etc. The display 42 is, for example, a Liquid Crystal Display (LCD), a CRT (Cathode Ray Tube) display, an organic EL (Electroluminescence) display, etc.

[0031] The input interface 43 accepts various input operations by the person performing the MRI examination, and outputs an electric signal indicating the contents of the accepted input operation to the processing circuit 50. For example, the input interface 43 accepts input operations such as acquisition conditions when acquiring MR data, generation conditions when generating MR data, reconstruction conditions when reconstructing a reconstructed image, and image processing conditions when generating a post-processed image from the reconstructed image. The input interface 43 is realized by, for example, a mouse, a keyboard, a touch panel, a trackball, a switch, a button, a joystick, a camera, an infrared sensor, a microphone, and the like. When the input interface 43 is a touch panel, the display 42 may be formed integrally with the input interface 43. The input interface 43 may be provided in the gantry device 10.

[0032] The processing circuitry 50 controls the overall operation of the MRI apparatus 1. The processing circuitry 50 sets sequence information in the sequence control circuit 31. The processing circuitry 50 executes, for example, an acquisition function 51, a reconstruction processing function 52, an image processing function 53, an output control function 54, and the like. The processing circuitry 50 realizes these functions by, for example, a hardware processor provided in a computer device executing a program (software) stored in a memory 41 which is a storage device (storage circuit).

[0033] A hardware processor refers to circuitry such as a CPU, a graphics processing unit (GPU), an application specific integrated circuit (ASIC), a programmable logic device (e.g., a simple programmable logic device (SPLD) or a complex programmable logic device (CPLD), a field programmable gate array (FPGA)), etc.

[0034] The acquisition function 51 acquires the MR data transferred by the sequence control circuit 31. The MR data is obtained by converting the MR signal into digital data by the receiving circuit .

[0035] The reconstruction processing function 52 generates a reconstructed image by performing a predetermined reconstruction process on the MR data acquired by the acquisition function 51. The reconstruction processing function 52 stores the generated reconstructed image in the memory 41.

[0036] The image processing function 53 converts the reconstructed image stored in the memory 41 into a three-dimensional image or cross-sectional image data of an arbitrary cross section by a known method based on an input operation received by the input interface 43. The image processing function 53 stores the converted cross-sectional image data in the memory 41 as an MR image.

[0037] The output control function 54 controls, for example, the display mode on the display 42. The output control function 54 outputs and displays the MR images generated by the image processing function 53 and stored in the memory 41 on the display 42. This allows the person performing the MRI examination to visually check the MR images displayed on the display 42 and perform a diagnosis or examination as to whether or not the subject P has a lesion. The output control function 54 may display a GUI image or the like for accepting various operations by the person performing the MRI examination.

[0038] MR images, cross-sectional images, and reconstructed images are examples of "magnetic resonance images."

[0039] (First embodiment) Next, the configuration of the static magnetic field magnet 12 included in the MRI apparatus 1 and the structure supporting the superconducting coil in the static magnetic field magnet 12 will be described. Fig. 2 is a diagram showing an example of the configuration of the superconducting magnet apparatus (static magnetic field magnet 12) according to the first embodiment. Fig. 2 shows a schematic configuration of the static magnetic field magnet 12 configured to support the superconducting coil 121 in a vacuum vessel 120 by suspending it from above by adiabatic load supports 122. More specifically, Fig. 2 shows a configuration in which each of the adiabatic load supports 122 arranged at two locations in the vacuum vessel 120 is connected to the center of the superconducting coil 121 via a thermal deformation cancellation mechanism 123.

[0040] The heat insulating load supporting material 122 is, for example, a rod or a cylindrical member made of fiber reinforced plastics (FRP). The inside of the vacuum vessel 120 is cooled to an extremely low temperature by, for example, a cooling device (not shown). Therefore, the outer shape of the superconducting coil 121 is thermally deformed, for example, by about 0.3%, by being cooled to an extremely low temperature. This thermal deformation of the outer shape of the superconducting coil 121 applies a load (stress) in a bending direction to the heat insulating load supporting material 122. FIG. 2 shows an example of a state in which the heat insulating load supporting material 122 is subjected to stress due to thermal contraction St as a result of the superconducting coil 121 thermally contracting (the outer shape shrinking) in an extremely low temperature environment. The heat contraction St is an example of a "first deformation amount".

[0041] Since the thermal deformation cancellation mechanism 123 deforms in a direction that cancels (offsets) the thermal deformation of the superconducting coil 121, no stress acts on the adiabatic load support 122. Fig. 2 shows an example of a state in which the thermal deformation cancellation mechanism 123 applies a deformation Rf to the side opposite to the thermal contraction St, so that no stress is generated in the adiabatic load support 122. As a result, in the static magnetic field magnet 12, the positional deviation of the superconducting coil 121 within the vacuum vessel 120 is reduced. The deformation Rf is an example of a "second deformation amount."

[0042] (First configuration of thermal deformation cancellation mechanism) Here, the structure of the thermal deformation cancellation mechanism 123 will be described. FIG. 3 is a diagram showing an example of the structure of the thermal deformation cancellation mechanism 123 that supports the superconducting coil 121 in the superconducting magnet device (static magnetic field magnet 12) according to the first embodiment. FIG. 3 shows an example of the structure of the thermal deformation cancellation mechanism 123 located on the right side of the paper surface of FIG. 2 in the static magnetic field magnet 12 shown in FIG. 2. FIG. 3(a) shows an example of the structure of the thermal deformation cancellation mechanism 123, and FIG. 3(b) shows an example of the relationship between the thermal contraction St applied to the insulating load support 122 when the superconducting coil 121 is thermally deformed and the deformation Rf of the thermal deformation cancellation mechanism 123. More specifically, FIG. 3(b) shows an example of the relationship between the thermal contraction St and the deformation Rf of the thermal deformation cancellation mechanism 123 when the superconducting coil 121 is thermally contracted.

[0043] First, the configuration of the thermal deformation cancellation mechanism 123 will be described with reference to (a) of Fig. 3. The thermal deformation cancellation mechanism 123 includes a plate material 1231, and fastening parts 1232a, 1232b, and 1232c. In the following description, when there is no need to distinguish between the fastening parts 1232a, 1232b, and 1232c, they will simply be referred to as "fastening parts 1232".

[0044] The plate material 1231 is a metal plate material that cancels (offsets) the amount of deformation applied to the thermally insulating load supporting material 122 due to the thermal deformation of the superconducting coil 121. The plate material 1231 cancels (offsets) the amount of deformation applied to the thermally insulating load supporting material 122 by thermally deforming in the same environment as the superconducting coil 121. The plate material 1231 has a curved shape with a curved portion whose center is concave toward the superconducting coil 121 side. The plate material 1231 deforms in a direction opposite to the direction in which the superconducting coil 121 thermally deforms according to the temperature inside the vacuum vessel 120 in which the plate material 1231 is housed together with the superconducting coil 121, and cancels (offsets) the deformation applied to the thermally insulating load supporting material 122 due to the thermal deformation generated in the superconducting coil 121. The plate material 1231 cancels (offsets) the deformation applied from the superconducting coil 121 to the thermally insulating load supporting material 122 due to the difference between the thermal expansion coefficient at which the superconducting coil 121 thermally deforms and the thermal expansion coefficient at which the plate material 1231 thermally deforms. The thermal expansion coefficient of the plate material 1231 is determined based on the thermal expansion coefficients known in advance for each material constituting (forming) the superconducting coil 121, and a material constituting (forming) the plate material 1231 is selected based on the determined thermal expansion coefficient. In the configuration of the thermal deformation cancellation mechanism 123 shown in FIG. 3(a), a material having a thermal expansion coefficient larger than that of the superconducting coil 121 is selected as the material for forming the plate material 1231.

[0045] Plate material 1231 is an example of a “thermal deformation member.” The thermal expansion coefficient at which superconducting coil 121 thermally deforms is an example of a “first thermal expansion coefficient,” and the thermal expansion coefficient at which plate material 1231 deforms due to heat is an example of a “second thermal expansion coefficient.”

[0046] The fastening parts 1232 are parts for connecting the plate material 1231 to the superconducting coil 121 or the heat-insulating load support 122. More specifically, the fastening parts 1232a and 1232b each connect the opposing end to the superconducting coil 121 so that the concave curved part of the plate material 1231 is concave toward the superconducting coil 121, and the fastening part 1232c connects the center of the curved part of the plate material 1231 to the heat-insulating load support 122. Since each of the fastening parts 1232 is also accommodated in the vacuum vessel 120 together with the superconducting coil 121 and the plate material 1231, it is possible that the fastening parts 1232 may be thermally deformed depending on the temperature in the vacuum vessel 120. In this case, the thermal expansion coefficient of the plate material 1231 may be determined so as to cancel (offset) the thermal deformation of the fastening parts 1232 as well, and a material for forming the plate material 1231 may be selected. In the following description, for ease of explanation, it is assumed that the fastening part 1232 does not undergo thermal deformation.

[0047] Next, with reference to Fig. 3(b), an example of the relationship between thermal contraction St and deformation Rf of thermal deformation cancellation mechanism 123 when superconducting coil 121 thermally contracts due to the inside of vacuum vessel 120 being made extremely low temperature will be described. Here, plate material 1231-1a shown in Fig. 3(b) has a thermal expansion coefficient according to the temperature inside vacuum vessel 120 that is larger than the thermal expansion coefficient of superconducting coil 121.

[0048] When the superconducting coil 121 thermally contracts due to the inside of the vacuum vessel 120 being cooled to an extremely low temperature, the fastening parts 1232a and 1232b are moved in a direction approaching each other, as shown by the movement Sm in Fig. 3(b). On the other hand, since the plate material 1231 has a thermal expansion coefficient relatively larger than that of the superconducting coil 121, the plate material 1231 thermally contracts in a direction in which the concave curved shape expands (a direction in which the concave curved portion expands and becomes flat), causing a deformation Rf toward the right side of the paper in Fig. 3(b). As a result, in the static magnetic field magnet 12, the thermal contraction St of the superconducting coil 121 relative to the heat-insulating load support 122, which occurs due to the inside of the vacuum vessel 120 being cooled to an extremely low temperature, is cancelled (offset), and the positional deviation of the superconducting coil 121 in the vacuum vessel 120 is reduced.

[0049] (Second configuration of the thermal deformation cancellation mechanism) Here, another structure of the thermal deformation cancellation mechanism 123 will be described. FIG. 4 is a diagram showing another example of the structure of the thermal deformation cancellation mechanism 123 that supports the superconducting coil 121 in the superconducting magnet device (static magnetic field magnet 12) according to the first embodiment. FIG. 4 also shows an example of the structure of the thermal deformation cancellation mechanism 123 located on the right side of the paper surface of FIG. 2 in the static magnetic field magnet 12 shown in FIG. 2, similar to the thermal deformation cancellation mechanism 123 of the second configuration shown in FIG. 3. FIG. 4(a) also shows an example of the structure of the thermal deformation cancellation mechanism 123, and FIG. 4(b) and FIG. 4(c) also show an example of the relationship between the thermal contraction St applied to the insulating load support member 122 when the superconducting coil 121 is thermally deformed and the deformation Rf of the thermal deformation cancellation mechanism 123. More specifically, Fig. 4(b) shows an example of the relationship between the thermal contraction St when the superconducting coil 121 thermally contracts and the deformation Rf of the thermal deformation canceling mechanism 123, and Fig. 4(c) shows an example of the relationship between the thermal contraction St when the superconducting coil 121 thermally expands and the deformation Rf of the thermal deformation canceling mechanism 123. In general, it is considered that the material constituting (forming) the superconducting coil 121 thermally contracts when the inside of the vacuum vessel 120 is cooled to an extremely low temperature, but for example, when the superconducting coil 121 is formed of ultra-high molecular weight polyethylene such as Dyneema (registered trademark), it is considered that the superconducting coil 121 thermally expands when the inside of the vacuum vessel 120 is cooled to an extremely low temperature.

[0050] First, the configuration of the thermal deformation cancellation mechanism 123 will be described with reference to (a) of Fig. 4. The thermal deformation cancellation mechanism 123 shown in (a) of Fig. 4 also includes a plate material 1231, a fastening part 1232a, a fastening part 1232b, and a fastening part 1232c. The fastening parts 1232 included in the thermal deformation cancellation mechanism 123 shown in (a) of Fig. 4 are similar to the fastening parts 1232 included in the thermal deformation cancellation mechanism 123 shown in (a) of Fig. 3. Therefore, a repeated description of the fastening parts 1232 included in the thermal deformation cancellation mechanism 123 shown in (a) of Fig. 4 will be omitted.

[0051] In the plate material 1231 provided in the thermal deformation cancellation mechanism 123 shown in Fig. 4(a), the plate material 1231, which has a curved shape with a central portion recessed toward the superconducting coil 121 side in the thermal deformation cancellation mechanism 123 shown in Fig. 3(a), is attached so that the front and back are reversed. In other words, in the thermal deformation cancellation mechanism 123 shown in Fig. 4(a), the plate material 1231 has a curved shape with a central portion having a curved portion that is convex on the side opposite to the superconducting coil 121. In the thermal deformation cancellation mechanism 123 shown in Fig. 4(a), the fastening parts 1232a and 1232b each connect the opposing end portion to the superconducting coil 121 so that the convex curved portion of the plate material 1231 is convex on the side opposite to the superconducting coil 121, and the fastening part 1232c connects the center of the curved portion of the plate material 1231 to the thermal insulation load support member 122. The plate material 1231 shown in Fig. 4(a) deforms in a direction opposite to the direction of thermal deformation of the superconducting coil 121 according to the temperature inside the vacuum vessel 120 in which the plate material 1231 is housed together with the superconducting coil 121, thereby canceling (offsetting) the deformation applied to the thermally insulating load supporting material 122 due to the thermal deformation generated in the superconducting coil 121. As with the plate material 1231 provided in the thermal deformation canceling mechanism 123 shown in Fig. 3(a), the thermal expansion coefficient of the plate material 1231 shown in Fig. 4(a) is determined based on the thermal expansion coefficients known in advance for each material constituting (forming) the superconducting coil 121, and the material constituting (forming) the plate material 1231 shown in Fig. 4(a) is selected based on the determined thermal expansion coefficient.

[0052] Next, with reference to Fig. 4(b), an example of the relationship between thermal contraction St and deformation Rf of thermal deformation cancellation mechanism 123 when superconducting coil 121 thermally contracts due to the inside of vacuum vessel 120 being made extremely low temperature will be described. Here, plate material 1231-2a shown in Fig. 4(b) has a thermal expansion coefficient according to the temperature inside vacuum vessel 120 that is smaller than the thermal expansion coefficient of superconducting coil 121.

[0053] When the superconducting coil 121 thermally contracts due to the inside of the vacuum vessel 120 being cooled to an extremely low temperature, the fastening parts 1232a and 1232b are also moved in a direction approaching each other as shown by the movement Sm in FIG. 4(b) in the static magnetic field magnet 12 shown in FIG. 4. In contrast, since the plate material 1231 has a thermal expansion coefficient relatively smaller than that of the superconducting coil 121, the convexly bulged curved shape is further pushed up, and a deformation Rf toward the right side of the paper in FIG. 4(b) occurs. In other words, in the thermal deformation cancellation mechanism 123 configured as shown in FIG. 4, the thermal contraction St of the superconducting coil 121 relative to the heat-insulating load support material 122, which occurs due to the inside of the vacuum vessel 120 being cooled to an extremely low temperature, is cancelled (offset) and the positional deviation of the superconducting coil 121 in the vacuum vessel 120 is reduced, as in the thermal deformation cancellation mechanism 123 configured as shown in FIG. 3.

[0054] Next, with reference to Fig. 4(c), an example of the relationship between thermal contraction St and deformation Rf of thermal deformation canceling mechanism 123 when superconducting coil 121 thermally expands due to the inside of vacuum vessel 120 being made extremely low temperature will be described. Here, plate material 1231-2a shown in Fig. 4(c) has a positive thermal expansion coefficient.

[0055] When the inside of the vacuum vessel 120 is cooled to an extremely low temperature and the superconducting coil 121 thermally expands, in the static magnetic field magnet 12 shown in Fig. 4, the fastening parts 1232a and 1232b are moved in directions away from each other, as shown by the movement Sm in Fig. 4(c). In contrast, the plate material 1231 shown in Fig. 4(c) has a positive thermal expansion coefficient, and therefore, when the inside of the vacuum vessel 120 is cooled to an extremely low temperature, it thermally contracts in a direction in which the curved shape that bulges out convexly expands (a direction in which the curved part of the convex shape tries to become concave and flat), causing a deformation Rf toward the left side of the paper in Fig. 4(c). As a result, even in the static magnetic field magnet 12 connected to the insulating load support 122 by the thermal deformation cancellation mechanism 123 of the configuration shown in Figure 4, the thermal contraction St of the superconducting coil 121 relative to the insulating load support 122, which occurs when the inside of the vacuum vessel 120 is cooled to an extremely low temperature, is canceled (offset), and the positional deviation of the superconducting coil 121 within the vacuum vessel 120 is reduced.

[0056] (Third configuration of thermal deformation cancellation mechanism) Here, another structure of the thermal deformation cancellation mechanism 123 will be described. FIG. 5 is a diagram showing another example of the structure of the thermal deformation cancellation mechanism 123 that supports the superconducting coil 121 in the superconducting magnet device (static magnetic field magnet 12) according to the first embodiment. FIG. 5 also shows an example of the structure of the thermal deformation cancellation mechanism 123 located on the right side of the paper surface of FIG. 2 in the static magnetic field magnet 12 shown in FIG. 2, similar to the thermal deformation cancellation mechanism 123 of the second configuration shown in FIG. 3 and FIG. 4. FIG. 5(a) also shows an example of the structure of the thermal deformation cancellation mechanism 123, and FIG. 5(b) and FIG. 5(c) also show an example of the relationship between the thermal contraction St applied to the insulating load support member 122 when the superconducting coil 121 is thermally deformed and the deformation Rf of the thermal deformation cancellation mechanism 123. More specifically, (b) of Figure 5 shows an example of the relationship between the thermal contraction St when the superconducting coil 121 thermally contracts and the deformation Rf of the thermal deformation cancellation mechanism 123, and (c) of Figure 5 shows an example of the relationship between the thermal contraction St when the superconducting coil 121 thermally expands and the deformation Rf of the thermal deformation cancellation mechanism 123.

[0057] First, the configuration of the thermal deformation cancellation mechanism 123 will be described with reference to (a) of FIG. 5. The thermal deformation cancellation mechanism 123 shown in (a) of FIG. 5 includes a plate material 1231a, a plate material 1231b, a fastening part 1232a, and a fastening part 1232b. In the thermal deformation cancellation mechanism 123 shown in (a) of FIG. 5, the fastening part 1232a connects the heat insulating load support material 122 and the plate material 1231a, and the fastening part 1232b connects the heat insulating load support material 122 and the plate material 1231b. Each fastening part 1232 is similar to each fastening part 1232 included in the thermal deformation cancellation mechanism 123 shown in (a) of FIG. 3. Therefore, a repeated description of each fastening part 1232 included in the thermal deformation cancellation mechanism 123 shown in (a) of FIG. 5 will be omitted.

[0058] The thermal deformation cancellation mechanism 123 shown in Fig. 5(a) is different from the thermal deformation cancellation mechanism 123 shown in Fig. 3(a) and Fig. 4(a) in that the plate material 1231 is divided into two, a plate material 1231a and a plate material 1231b. More specifically, the plate material 1231 of the thermal deformation cancellation mechanism 123 shown in Fig. 5(a) has a shape in which the convex curved portion of the plate material 1231 of the thermal deformation cancellation mechanism 123 shown in Fig. 4(a) is divided into two at a central dividing point. In other words, the plate material 1231 of the thermal deformation cancellation mechanism 123 shown in Fig. 5(a) forms a curved shape having a curved portion whose central portion is convex on the opposite side to the superconducting coil 121 by a pair of plate materials 1231, the plate material 1231a and the plate material 1231b. In the configuration of the thermal deformation cancellation mechanism 123 shown in Fig. 5(a), the fastening part 1232a is connected to the end of the plate material 1231a that corresponds to the central position of the plate material 1231a, and the fastening part 1232b is connected to the end of the plate material 1231b that corresponds to the central position of the plate material 1231b, and the fastening part 1232a and the fastening part 1232b are each connected to the heat-insulating load support material 122. Furthermore, in the configuration of the thermal deformation cancellation mechanism 123 shown in Fig. 5(a), the end of the plate material 1231a and the plate material 1231b that is not connected to the corresponding fastening part 1232 is directly connected to the superconducting coil 121. Here, the direct connection of the end of the plate material 1231a and the plate material 1231b that is not connected to the fastening part 1232 to the superconducting coil 121 is rigidly connected to the superconducting coil 121 by, for example, a bolt or the like. In the following description, when there is no need to distinguish between the plate material 1231a and the plate material 1231b, they will simply be referred to as "plate material 1231."

[0059] The plate material 1231 shown in Fig. 5(a) cancels (offsets) the deformation applied to the thermally insulating load supporting material 122 due to the thermal deformation occurring in the superconducting coil 121 by deforming the end portion to which the fastening part 1232 is connected in accordance with the temperature inside the vacuum vessel 120 in which the plate material 1231 shown in Fig. 5(a) is connected in accordance with the temperature inside the vacuum vessel 120 in which the plate material 1231 is housed together with the superconducting coil 121. The thermal expansion coefficient of the plate material 1231 shown in Fig. 5(a) is determined based on the thermal expansion coefficients known in advance for each material constituting (forming) the superconducting coil 121, similar to the plate material 1231 provided in the thermal deformation canceling mechanism 123 shown in Fig. 3(a) and Fig. 4(a), and the material constituting (forming) the plate material 1231 shown in Fig. 5(a) is selected based on the determined thermal expansion coefficient.

[0060] Next, with reference to Fig. 5(b), an example of the relationship between thermal contraction St and deformation Rf of thermal deformation cancellation mechanism 123 when superconducting coil 121 thermally contracts due to the inside of vacuum vessel 120 being made extremely low temperature will be described. Here, each of plate material 1231a-3a and plate material 1231b-3a shown in Fig. 5(b) has a smaller thermal expansion coefficient according to the temperature inside vacuum vessel 120 than that of superconducting coil 121.

[0061] When the superconducting coil 121 is thermally contracted by cooling the inside of the vacuum vessel 120 to an extremely low temperature, the fastening parts 1232a and 1232b are also moved in a direction approaching each other as shown by the movement Sm in FIG. 5(b) in the static magnetic field magnet 12 shown in FIG. 5(b) in the same manner as in FIG. 3(b) and FIG. 4(b). As a result, the plate material 1231a and the plate material 1231b shown in FIG. 5(b) are each caused to undergo a deformation Rf toward the right side of the paper surface of FIG. 5(b). As a result, even in the static magnetic field magnet 12 connected to the thermal deformation canceling mechanism 123 of the configuration shown in FIG. 5(b), the thermal contraction St of the superconducting coil 121 relative to the thermal insulation load supporting material 122 caused by cooling the inside of the vacuum vessel 120 to an extremely low temperature is cancelled (offset), and the positional deviation of the superconducting coil 121 in the vacuum vessel 120 is reduced.

[0062] Next, with reference to Fig. 5(c), an example of the relationship between thermal contraction St and deformation Rf of thermal deformation cancellation mechanism 123 when superconducting coil 121 thermally expands due to the inside of vacuum vessel 120 being made extremely low temperature will be described. Here, each of plate material 1231a-3b and plate material 1231b-3b shown in Fig. 5(c) has a positive thermal expansion coefficient.

[0063] When the superconducting coil 121 thermally expands due to the inside of the vacuum vessel 120 being cooled to an extremely low temperature, even in the static magnetic field magnet 12 shown in Fig. 5, the fastening parts 1232a and 1232b are moved in directions away from each other, as shown by the movement Sm in Fig. 5(c), similar to Fig. 4(c). As a result, the plates 1231a and 1231b shown in Fig. 5(c) are each deformed Rf toward the left side of the paper surface of Fig. 5(c). As a result, even in the static magnetic field magnet 12 connected to the thermal deformation canceling mechanism 123 shown in Fig. 5, the thermal contraction St of the superconducting coil 121 relative to the thermal insulation load supporting material 122, which occurs due to the inside of the vacuum vessel 120 being cooled to an extremely low temperature, is cancelled (offset), and the positional deviation of the superconducting coil 121 in the vacuum vessel 120 is reduced.

[0064] As described above, in the static magnetic field magnet 12 of the first embodiment, the superconducting coil 121 and the heat-insulating load support 122 are connected by the thermal deformation canceling mechanism 123 in the vacuum vessel 120. In the static magnetic field magnet 12 of the first embodiment, the thermal deformation canceling mechanism 123 generates a deformation Rf in a direction that cancels (offsets) the thermal contraction St that occurs in the superconducting coil 121 due to cooling the inside of the vacuum vessel 120 to an extremely low temperature. This reduces the positional deviation of the superconducting coil 121 in the vacuum vessel 120.

[0065] Second Embodiment Incidentally, in the static magnetic field magnet 12, the superconducting coil 121 may be housed in the vacuum vessel 120 while being housed in a radiation shield. The configuration of the static magnetic field magnet 12 in this case and the structure supporting the superconducting coil in the static magnetic field magnet 12 will be described below. Fig. 6 is a diagram showing an example of the configuration of a superconducting magnet device (static magnetic field magnet 12) according to the second embodiment. Fig. 6 shows a schematic configuration of the static magnetic field magnet 12 configured to support the superconducting coil 121 housed in a radiation shield 125 within the vacuum vessel 120 by being suspended from above by adiabatic load supports 122. Figure 6(a) shows a schematic configuration of a static magnetic field magnet 12 of a second embodiment, in which a superconducting coil 121 housed in a radiation shield 125 is supported within a vacuum vessel 120 by being suspended from above by an insulating load support 122, and Figure 6(b) shows, for reference, a schematic configuration of a conventional static magnetic field magnet 12 in which a superconducting coil 121 housed in a radiation shield 125 is supported within a vacuum vessel 120.

[0066] The components of each static magnetic field magnet 12 shown in Fig. 6 include components similar to those of the static magnetic field magnet 12 of the first embodiment. Therefore, in the following description, the same reference numerals are given to the components similar to those of the static magnetic field magnet 12 of the first embodiment, and detailed description will be omitted. In the following description, in order to distinguish between the static magnetic field magnet 12 of the first embodiment, the static magnetic field magnet 12 of the second embodiment, and the static magnetic field magnet 12 of the conventional configuration, the static magnetic field magnet 12 of the first embodiment will be referred to as "static magnetic field magnet 12A", the static magnetic field magnet 12 of the second embodiment will be referred to as "static magnetic field magnet 12B", and the static magnetic field magnet 12 of the conventional configuration will be referred to as "static magnetic field magnet 12C".

[0067] First, for comparison, the configuration of the static magnetic field magnet 12C shown in Fig. 6(b) will be described. In the case of a conventional static magnetic field magnet configuration in which a superconducting coil is placed in a vacuum vessel while being housed in a radiation shield, a configuration is conceivable in which each of the thermal insulation load supports 122 arranged at two locations in the radiation shield 125 is connected to the superconducting coil 121 by fastening parts 126, and each of the thermal insulation load supports 122 arranged at two locations in the vacuum vessel 120 is connected to the radiation shield 125 by fastening parts 126, as shown in Fig. 6(b). In this configuration, the inside of the vacuum vessel 120 is cooled to an extremely low temperature, so that the superconducting coil 121 and the radiation shield 125 are thermally deformed, and stress due to thermal contraction St is applied to each of the thermal insulation load supports 122. FIG. 6(b) shows an example of a state in which the superconducting coil 121 and the radiation shield 125 each undergo thermal contraction (shrinkage of their external dimensions) in an extremely low temperature environment, resulting in stress being applied to each insulating load support 122 due to thermal contraction St.

[0068] In contrast, in the static magnetic field magnet 12B, as shown in (a) of FIG. 6, the adiabatic load support members 122 arranged at two positions in the vacuum vessel 120 support the superconducting coil 121 and the radiation shield 125 via the thermal deformation canceling mechanism 123. In the static magnetic field magnet 12B, the thermal deformation canceling mechanism 123 is deformed in a direction that cancels (offsets) the thermal deformation of the superconducting coil 121 and the radiation shield 125, as in the static magnetic field magnet 12A, so that no stress acts on the adiabatic load support member 122. (a) of FIG. 6 shows an example of a state in which the adiabatic load support member 122 is subjected to stress due to thermal contraction St as a result of the superconducting coil 121 and the radiation shield 125 being thermally contracted (their external shapes being shrunk) in an extremely low temperature environment. (a) of FIG. 6 also shows an example of a state in which no stress is generated in the adiabatic load support member 122 by the thermal deformation canceling mechanism 123 applying deformation Rf to the side opposite to the thermal contraction St. As a result, in the static magnetic field magnet 12B as well, deviation in the positions of the superconducting coil 121 and the radiation shield 125 within the vacuum vessel 120 is reduced, similar to the static magnetic field magnet 12A.

[0069] (Configuration of thermal deformation cancellation mechanism) Here, the structure of the thermal deformation cancellation mechanism 123 provided in the static magnetic field magnet 12B will be described. Fig. 7 is a diagram showing an example of the structure of the thermal deformation cancellation mechanism 123 that supports the superconducting coil 121 (including the radiation shield 125) in the superconducting magnet device (static magnetic field magnet 12B) according to the second embodiment. Fig. 7 shows an example of the structure of the thermal deformation cancellation mechanism 123 located on the right side of the paper surface of Fig. 6 in the static magnetic field magnet 12B shown in Fig. 6.

[0070] The thermal deformation cancellation mechanism 123 includes a plate material 1231-1, a plate material 1231a-3, a plate material 1231b-3, and fastening parts 1232a, 1232b, 1232c, 1232d, and 1232e. In the following description, when fastening parts 1232b, 1232c, 1232d, and 1232e are not to be distinguished from one another, they are simply referred to as "fastening parts 1232."

[0071] Plate material 1231-1 is similar to plate material 1231 having a curved shape with a central portion recessed toward superconducting coil 121, which is provided in thermal deformation cancellation mechanism 123 of static magnetic field magnet 12A of the first configuration shown in Fig. 3. More specifically, plate material 1231-1 is similar to plate material 1231-1a shown in Fig. 3(b). Plate material 1231a-3 and plate material 1231b-3 are similar to plate material 1231a and plate material 1231b, respectively, which are configured to be divided into two and are provided in thermal deformation cancellation mechanism 123 of static magnetic field magnet 12A of the third configuration shown in Fig. 5. More specifically, the plate materials 1231a-3 and 1231b-3 are similar to the plate materials 1231a-3a and 1231b-3a shown in Fig. 5(b), or the plate materials 1231a-3b and 1231b-3b shown in Fig. 5(c). Therefore, a repeated description of the plate materials 1231 included in the thermal deformation cancellation mechanism 123 shown in Fig. 7 will be omitted.

[0072] Each of the fastening parts 1232 is similar to each of the fastening parts 1232 provided in the thermal deformation cancellation mechanism 123 of the static magnetic field magnet 12A of the first embodiment shown in Figures 3 to 5. However, in the thermal deformation cancellation mechanism 123 shown in Figure 7, each of the fastening parts 1232a and 1232b connects the superconducting coil 121 and the plate material 1231-1, the fastening part 1232c connects the thermal insulation load supporting material 122 and the plate material 1231-1, the fastening part 1232d connects the thermal insulation load supporting material 122 and the plate material 1231a-3, and the fastening part 1232e connects the thermal insulation load supporting material 122 and the plate material 1231b-3.

[0073] With this configuration, in static magnetic field magnet 12B, thermal deformation cancellation mechanism 123 connects superconducting coil 121 and radiation shield 125 to the corresponding heat-insulating load support member 122. In thermal deformation cancellation mechanism 123 provided in static magnetic field magnet 12B, a configuration of plate material 1231-1, fastening part 1232a, fastening part 1232b, and fastening part 1232c generates deformation Rf in a direction that cancels (offsets) thermal contraction St that occurs in superconducting coil 121 due to cooling the inside of vacuum vessel 120 to an extremely low temperature. Furthermore, in the thermal deformation canceling mechanism 123 provided in the static magnetic field magnet 12B, the plate material 1231a-3, the plate material 1231b-3, the fastening part 1232d, and the fastening part 1232e are configured to generate a deformation Rf in a direction that cancels (offsets) the thermal contraction St generated in the radiation shield 125 by cooling the inside of the vacuum vessel 120 to an extremely low temperature. At this time, each deformation Rf generated by the thermal deformation canceling mechanism 123 only needs to correspond to the thermal contraction St generated by the superconducting coil 121 and the thermal contraction St generated by the radiation shield 125, respectively, and does not necessarily have to be the same in magnitude. As a result, in the static magnetic field magnet 12B as well, the thermal contraction St of the superconducting coil 121 and the radiation shield 125 with respect to the adiabatic load supporting member 122 generated by cooling the inside of the vacuum vessel 120 to an extremely low temperature is canceled (offset), and the positional deviation of the superconducting coil 121 and the radiation shield 125 in the vacuum vessel 120 is reduced.

[0074] 7 shows the structure of the thermal deformation cancellation mechanism 123 that connects each of the superconducting coil 121 and the radiation shield 125 to the corresponding adiabatic load support 122 by combining the structures of the thermal deformation cancellation mechanism 123 in each of the static magnetic field magnet 12A of the first configuration shown in FIG. 3 and the static magnetic field magnet 12A of the third configuration shown in FIG. 5. However, the structure of the thermal deformation cancellation mechanism 123 that connects each of the superconducting coil 121 and the radiation shield 125 to the corresponding adiabatic load support 122 is not limited to the structure shown in FIG. 7. In other words, the structure combined in the thermal deformation cancellation mechanism 123 that connects each of the superconducting coil 121 and the radiation shield 125 to the corresponding adiabatic load support 122 may be a structure that combines the structures of any of the thermal deformation cancellation mechanisms 123 of the static magnetic field magnet 12A of the first embodiment shown in FIG. 3 to FIG. 5.

[0075] In the thermal deformation cancellation mechanism 123 shown in Fig. 7, the plate material 1231-1 is an example of a "first thermal deformation member." In the thermal deformation cancellation mechanism 123 shown in Fig. 7, the plate material 1231a-3 and the plate material 1231b-3 are an example of a "second thermal deformation member."

[0076] The relationship between the thermal contraction St and the deformation Rf of the thermal deformation cancellation mechanism 123 when the superconducting coil 121 or the radiation shield 125 thermally contracts or expands due to the inside of the vacuum vessel 120 being at an extremely low temperature can be easily considered based on the example of the relationship between the thermal contraction St and the deformation Rf in the thermal deformation cancellation mechanism 123 of the static magnetic field magnet 12A of the first embodiment described using Figures 3 to 5. Therefore, a detailed description of the example of the relationship between the thermal contraction St and the deformation Rf in the thermal deformation cancellation mechanism 123 of the static magnetic field magnet 12B will be omitted.

[0077] As described above, in the static magnetic field magnet 12B of the second embodiment, the superconducting coil 121 and the radiation shield 125 are each connected to the thermally insulated load supporting material 122 by the thermal deformation canceling mechanism 123 in the vacuum vessel 120. In the static magnetic field magnet 12B of the second embodiment, the thermal deformation canceling mechanism 123 generates a deformation Rf in a direction that cancels (offsets) the thermal contraction St that occurs in the superconducting coil 121 and the radiation shield 125 due to cooling the inside of the vacuum vessel 120 to an extremely low temperature. As a result, in the static magnetic field magnet 12B of the second embodiment, even if the superconducting coil 121 and the radiation shield 125 are thermally deformed due to cooling the inside of the vacuum vessel 120 to an extremely low temperature, the thermal deformation applied to the thermally insulated load supporting material 122 is canceled (offsets) and the positional deviation of the superconducting coil 121 and the radiation shield 125 in the vacuum vessel 120 is reduced.

[0078] Moreover, in the static magnetic field magnet 12B of the second embodiment, each of the superconducting coil 121 and the radiation shield 125 is connected to the corresponding heat-insulating load support 122 by one thermal deformation canceling mechanism 123. Therefore, the static magnetic field magnet 12B of the second embodiment has a configuration that is more resistant to vibration of the superconducting coil 121 than the conventional static magnetic field magnet 12C shown in FIG. 6(b). The vibration of the superconducting coil 121 includes, for example, vibration generated in the superconducting coil 121 itself when a strong static magnetic field is generated, and vibration applied to the superconducting coil 121 from the outside. The vibration generated in the superconducting coil 121 itself includes, for example, vibration generated when a strong static magnetic field is generated by receiving power from the static magnetic field power supply 32, and vibration generated by the interaction between the static magnetic field generated by the superconducting coil 121 and the gradient magnetic field (which can also be said to be an alternating magnetic field because the magnetic field strength changes along each of the X-axis, Y-axis, and Z-axis) generated by the gradient magnetic field coil 14. The vibrations applied to the superconducting coil 121 from the outside include, for example, vibrations applied when the MRI apparatus 1 is transported for installation in a medical facility.

[0079] (Third embodiment) In the first and second embodiments, the static magnetic field magnet 12 has been described with a configuration in which the superconducting coil 121 is accommodated in the vacuum vessel 120 by being suspended from above by the heat-insulating load support 122. However, in practice, it is preferable to support the superconducting coil 121 from a plurality of directions in the vacuum vessel 120, including the need to increase the resistance of the superconducting coil 121 to vibration in the static magnetic field magnet 12. The configuration of the static magnetic field magnet 12 in this case will be described below. FIG. 8 is a diagram showing an example of a configuration for supporting the superconducting coil 121 in the superconducting magnet device (static magnetic field magnet 12) according to the embodiment. FIG. 8(a) shows an example of the static magnetic field magnet 12 with a configuration in which the superconducting coil 121 is supported from a plurality of directions in the vacuum vessel 120. In FIG. 8(a), the superconducting coil 121 (superconducting coil 121 accommodated in a radiation shield 125) having the same configuration as the static magnetic field magnet 12B shown in FIG. 6(a) is supported in the vacuum vessel 120 from a plurality of directions so as to surround it. Each of Fig. 8(b-1) and Fig. 8(b-2) shows an example of the static magnetic field magnet 12 configured as shown in Fig. 8(a) when viewed from the direction in which the subject P is introduced into the MRI apparatus 1 (the Y-axis direction in Fig. 1). In the following description, the static magnetic field magnet 12 configured as shown in Fig. 8 is referred to as "static magnetic field magnet 12D". In the following description, the superconducting coil 121 housed in the radiation shield 125 housed in the vacuum vessel 120 in the static magnetic field magnet 12D is simply referred to as "superconducting coil 121".

[0080] In the static magnetic field magnet 12D, as shown in (a) of Fig. 8, the heat insulating load supports 122 are arranged in the vertical direction of the paper surface of (a) of Fig. 8 (Z-axis direction in Fig. 1) and the horizontal direction of the paper surface of (a) of Fig. 8 (Y-axis direction in Fig. 1) in a vacuum vessel 120. In this case, in the static magnetic field magnet 12D, the arrangement of the heat insulating load supports 122 in the horizontal direction of the paper surface of (a) of Fig. 8 may be such that they form a triangle on the end side of the superconducting coil 121 (for example, the introduction port side of the subject P), that is, they form a triangular prism surrounding the superconducting coil 121, as shown in (b-1) of Fig. 8. In the static magnetic field magnet 12D, the arrangement of the insulating load supports 122 in the left-right direction of the paper surface of Figure 8(a) may be such that they form a quadrilateral (e.g., a square) on the end side of the superconducting coil 121, that is, a rectangular prism surrounding the superconducting coil 121, as shown in Figure 8(b-2).

[0081] In the static magnetic field magnet 12D, as shown in FIG. 8(a), each of the arranged adiabatic load supports 122 is fastened in the vacuum vessel 120 by the fastening parts 130. That is, in the static magnetic field magnet 12D, both ends of each of the adiabatic load supports 122 are fastened in the vacuum vessel 120 by the fastening parts 130. In FIG. 8(b-1) and FIG. 8(b-2), each of the adiabatic load supports 122 is fastened in the vacuum vessel 120 by the fastening parts 130 at the vertices of a triangle or a rectangle. The fastening parts 130 are parts for connecting the vacuum vessel 120 and the adiabatic load supports 122. The fastening parts 130 may be the same parts as the fastening parts 1232 provided in the thermal deformation cancellation mechanism 123 of the static magnetic field magnet 12A of the first embodiment shown in FIG. 3 to FIG. 5 and the static magnetic field magnet 12B of the second embodiment shown in FIG. 7, or may be different parts.

[0082] In the static magnetic field magnet 12D, as shown in (a) of FIG. 8, the superconducting coils 121 are connected to the respective heat-insulating load supports 122 arranged (fastened) in the vacuum vessel 120 via the thermal deformation cancellation mechanisms 123. The structure of the thermal deformation cancellation mechanism 123 in this case, that is, the combination of the shape of the plate material 1231 and the arrangement of the fastening parts 1232, may be equivalent to the structure of the thermal deformation cancellation mechanism 123 shown in FIG. 7. In other words, the combination of the shape of the plate material 1231 and the arrangement of the fastening parts 1232 in the thermal deformation cancellation mechanism 123 shown in (a) of FIG. 8 may be a combination of the shape of the plate material 1231 and the arrangement of the fastening parts 1232 in any one of the thermal deformation cancellation mechanisms 123 of the static magnetic field magnet 12A of the first embodiment shown in FIGS. 3 to 5.

[0083] With this configuration, in the static magnetic field magnet 12D, a plurality of heat insulating load supports 122 are arranged so as to surround the superconducting coil 121 (including the radiation shield 125) in the vacuum vessel 120, and a thermal deformation canceling mechanism 123 connecting each heat insulating load support 122 and the superconducting coil 121 generates a deformation Rf in a direction that cancels (offsets) the thermal contraction St that occurs in the superconducting coil 121 (including the radiation shield 125) by cooling the inside of the vacuum vessel 120 to an extremely low temperature. This reduces the positional deviation of the superconducting coil 121 (including the radiation shield 125) in the vacuum vessel 120.

[0084] Moreover, in the static magnetic field magnet 12D, a plurality of heat insulating load supports 122 are arranged to surround and support the superconducting coil 121 (including the radiation shield 125) from a plurality of directions within the vacuum vessel 120. This makes it possible for the static magnetic field magnet 12D to have increased resistance to vibrations that occur when the superconducting coil 121 generates a strong static magnetic field and vibrations that are applied to the superconducting coil 121 from the outside.

[0085] In FIG. 8(a), the static magnetic field magnet 12D is shown in a configuration in which all the adiabatic load supports 122 are connected to the superconducting coil 121 via the thermal deformation cancellation mechanism 123, but this is merely an example, and as long as the configuration can increase the resistance to vibration, the connection to the superconducting coil 121 via the thermal deformation cancellation mechanism 123 may be omitted in any of the adiabatic load supports 122 included in the static magnetic field magnet 12D. In other words, the configuration is not limited to the case in which all the adiabatic load supports 122 are connected to the superconducting coil 121 via the thermal deformation cancellation mechanism 123. For example, in the example shown in FIG. 8(b-1) and FIG. 8(b-2), the connection to the superconducting coil 121 via the thermal deformation cancellation mechanism 123 may be omitted in the adiabatic load supports 122 arranged at positions forming a triangle or a rectangle. In other words, in the example shown in Figure 8 (b-1) or Figure 8 (b-2), only the insulating load support 122 (the insulating load support 122 arranged in the left-right direction of the paper in Figure 8 (a)) that is arranged at the vertices of the triangle or rectangle in the depth direction of the paper (the Y-axis direction in Figure 1) may be connected to the superconducting coil 121 via the thermal deformation cancellation mechanism 123.

[0086] As described above, in the static magnetic field magnet 12D of the third embodiment, a plurality of insulating load supports 122 are arranged within the vacuum vessel 120 so as to surround the superconducting coil 121 (including the radiation shield 125), and the superconducting coil 121 (including the radiation shield 125) is connected via a thermal deformation cancellation mechanism 123 corresponding to each insulating load support 122. By cooling the inside of the vacuum vessel 120 to an extremely low temperature, the thermal deformation acting on the insulating load support 122 can be canceled (offset), and the resistance of the superconducting coil 121 (including the radiation shield 125) to vibration can be increased.

[0087] As described above, in the superconducting magnet device (static magnetic field magnet 12) of the embodiment, the thermal deformation cancellation mechanism 123 that connects the superconducting coil 121 (which may include the radiation shield 125) housed in the vacuum vessel 120 to the heat-insulating load support member 122 that supports the superconducting coil 121 generates a deformation Rf in a direction that cancels (offsets) the thermal contraction St due to the thermal deformation that occurs in the superconducting coil 121 when the inside of the vacuum vessel 120 is cooled to an extremely low temperature. This makes it possible to reduce the positional deviation of the superconducting coil 121 in the vacuum vessel 120.

[0088] Furthermore, in the superconducting magnet device (static magnetic field magnet 12) of the embodiment, multiple insulating load supports 122 are arranged inside the vacuum vessel 120, and the superconducting coil 121 (which may include a radiation shield 125) is connected via a thermal deformation cancellation mechanism 123 corresponding to each insulating load support 122, thereby making it possible to increase the resistance to vibration in the superconducting magnet device.

[0089] As a result, a magnetic resonance imaging apparatus (MRI apparatus 1) using the superconducting magnet device of the embodiment can capture more suitable tomographic images (MR images) of the subject P, enabling diagnosis and examination of the subject P to be performed more smoothly.

[0090] In the above-described embodiment, the superconducting magnet device (static magnetic field magnet 12) is formed in a hollow, approximately cylindrical shape, and the imaging site of the subject P is moved into the cavity of the static magnetic field magnet 12, the gradient magnetic field coil 14, and the RF coil 16, that is, into the imaging port (bore) of the gantry device 10 to capture a tomographic image (MR image) of the subject P. However, the shape of the superconducting magnet device used in the MRI device may be a shape other than a hollow, approximately cylindrical shape. For example, an MRI device may be provided with two separate superconducting magnet devices, and each superconducting magnet device may sandwich the subject P to generate a strong static magnetic field to capture a tomographic image (MR image). An MRI device with such a configuration may also employ a configuration similar to that of the superconducting magnet device of the embodiment. That is, as in the superconducting magnet device of the embodiment, the thermal deformation applied to the insulating load support material from the superconducting coil (which may include a radiation shield) thermally deformed by cooling the inside of the vacuum container to an extremely low temperature may be canceled (offset) by a thermal deformation cancellation mechanism that connects the superconducting coil to the insulating load support material that supports the superconducting coil in the vacuum container, thereby reducing the positional deviation of the superconducting coil in the vacuum container. In this case, the configuration of the superconducting magnet device or magnetic resonance imaging device and the structure of the thermal deformation cancellation mechanism may be equivalent to the configuration of the superconducting magnet device or magnetic resonance imaging device and the structure of the thermal deformation cancellation mechanism of the above-mentioned embodiment. Therefore, detailed explanations of the configuration of the superconducting magnet device or magnetic resonance imaging device and the structure of the thermal deformation cancellation mechanism when the shape of the superconducting magnet device used in the MRI device is other than a hollow, approximately cylindrical shape will be omitted.

[0091] In the above-mentioned embodiment, the superconducting magnet device (static magnetic field magnet 12) is used in a magnetic resonance imaging device (MRI device 1), but this is merely an example, and the device or system in which the superconducting magnet device of the embodiment is used is not limited to a magnetic resonance imaging device, as long as the device or system uses the superconducting magnet device. For example, the superconducting magnet device of the embodiment may be applied to a device or system in a field other than the medical field, such as a linear motor car. Even in this case, the configuration of the superconducting magnet device and the structure of the thermal deformation cancellation mechanism may be equivalent to the configuration of the superconducting magnet device and the structure of the thermal deformation cancellation mechanism of the above-mentioned embodiment. Therefore, detailed description of the configuration of the superconducting magnet device and the structure of the thermal deformation cancellation mechanism in this case will be omitted.

[0092] According to at least one of the embodiments described above, there is provided a superconducting magnet device (static magnetic field magnet 12) in which at least a superconducting coil (121) is accommodated in a vacuum vessel (120) while being supported by an adiabatic load support (122), and the adiabatic load support supports the superconducting coil via a thermal deformation cancellation mechanism that generates a second deformation amount (deformation Rf) in a direction that offsets a first deformation amount (thermal contraction St) applied from the superconducting coil to the adiabatic load support due to thermal deformation generated in the superconducting coil when the inside of the vacuum vessel is cooled to an extremely low temperature, and the thermal deformation cancellation mechanism is at least made of a material having a second thermal expansion coefficient determined based on a first thermal expansion coefficient of a material forming the superconducting coil, and includes a thermal deformation member (plate material 1231) that generates the second deformation amount by thermally deforming in the same environment as the superconducting coil, thereby providing a structure in the superconducting magnet device in which a load is not generated on the load support (adiabatic load support) due to thermal deformation of the superconducting coil accommodated in the vacuum vessel.

[0093] Although some embodiments have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope of the invention and its equivalents as described in the claims, as well as in the scope and spirit of the invention. [Explanation of symbols]

[0094] 1 MRI device, 10 stand device, 12, 12A, 12B, 12D static magnetic field magnet, 120 vacuum vessel, 121 superconducting coil, 122 thermal insulation load support, 123 thermal deformation cancellation mechanism, 1231, 1231-1, 1231-1a, 1231-1b, 1231-2a, 123 1-2b,1231a,1231b,1231a-3,1231b-3,1231a-3a,1231b-3a,1231a-3b,1231b-3b· · Plate material, 1232,1232a,1232b,1232c,1232d,1232e · Fastening parts, 125 · Radiation shield, 130 · Fastening Component, 14 ··· gradient magnetic field coil, 16 ··· RF coil, 18 ··· RF coil, 18c ··· coil cable, 20 ··· bed device, 22 ··· base, 24 ··· tabletop, 26 ··· coil port, 30 ··· control device, 31 ··· sequence control circuit, 32 ··· static magnetic field power supply, 33 ··· gradient magnetic field power supply, 34 ··· transmission circuit, 35 ··· reception circuit, 36 ··· bed control circuit, 40 ··· console device, 41 ··· memory, 42 ··· display, 43 ··· input interface, 50 ··· processing circuit, 51 ··· acquisition function, 52 ··· reconstruction processing function, 53 ··· image processing function, 54 ··· output control function

Claims

1. A superconducting magnet apparatus in which at least a superconducting coil is accommodated in a vacuum vessel while being supported by a heat-insulating load support, the adiabatic load support supports the superconducting coil via a thermal deformation canceling mechanism that generates a second deformation amount in a direction that cancels a first deformation amount applied to the adiabatic load support from the superconducting coil due to thermal deformation generated in the superconducting coil when the inside of the vacuum vessel is cooled to an extremely low temperature, the thermal deformation cancellation mechanism is at least made of a material having a second thermal expansion coefficient determined based on a first thermal expansion coefficient of a material forming the superconducting coil, and includes a thermal deformation member that generates the second deformation amount by thermally deforming in the same environment as the superconducting coil. Superconducting magnet device.

2. The first thermal expansion coefficient and the second thermal expansion coefficient are different thermal expansion coefficients.

2. The superconducting magnet device according to claim 1.

3. The thermal deformation member is The plate material has a curved shape with a concave curved portion at the center, each of the opposing ends of the curved portion is connected to the superconducting coil such that the curved portion is concave toward the superconducting coil; The center of the curved portion is connected to the insulating load support; the second coefficient of thermal expansion is greater than the first coefficient of thermal expansion; The curved portion is thermally deformed at the second thermal expansion coefficient in the same environment as the superconducting coil, thereby generating the second deformation amount.

3. The superconducting magnet device according to claim 2.

4. The thermal deformation member is The plate material has a curved shape with a convex curved portion at the center, each of the opposing ends of the curved portion is connected to the superconducting coil such that the curved portion is convex toward an opposite side to the superconducting coil; The center of the curved portion is connected to the insulating load support; the second coefficient of thermal expansion is smaller than the first coefficient of thermal expansion; The curved portion is thermally deformed at the second thermal expansion coefficient in the same environment as the superconducting coil, thereby generating the second deformation amount.

3. The superconducting magnet device according to claim 2.

5. The thermal deformation member is A curved plate having a curved portion with a convex central portion is composed of a pair of plate members divided into two at a dividing point in the center of the curved portion, an end portion of each of the divided plate members opposite to the divided portion is connected to the superconducting coil such that the curved portion is convex toward an opposite side to the superconducting coil; The end portion of each of the divided plates is connected to the heat-insulating load-supporting material, the second coefficient of thermal expansion is smaller than the first coefficient of thermal expansion; the end portion on the side of the divided portion is thermally deformed with the second thermal expansion coefficient under the same environment as that of the superconducting coil, thereby generating the second deformation amount.

3. The superconducting magnet device according to claim 2.

6. The superconducting coil is housed in a radiation shield; the heat-insulating load support member supports the superconducting coil together with the radiation shield via the thermal deformation cancellation mechanism; The thermal deformation cancellation mechanism includes: a first thermal deformation member which is the thermal deformation member that connects at least the superconducting coil and the thermally insulating load support; A second thermal deformation member that is the thermal deformation member that connects at least the radiation shield and the heat-insulating load support; Equipped with The first thermal deformation member includes: a first plate material having a first curved shape with a first curved portion having a concave central portion; each of the opposing ends of the first curved portion is connected to the superconducting coil such that the first curved portion is concave toward the superconducting coil; a center of the first curved portion is connected to the insulating load support; The second thermal expansion coefficient (2-1) of the first thermal deformation member is a thermal expansion coefficient that is greater than the first thermal expansion coefficient (1-1) of the superconducting coil, The first curved portion is thermally deformed at the second-1st thermal expansion coefficient under the same environment as the superconducting coil, thereby generating the second deformation amount; The second thermal deformation member includes: a second curved plate member having a convex second curved portion at a central portion thereof is composed of a pair of second plate members divided into two at a central dividing portion of the second curved portion, an end portion of each of the divided second plate members opposite to the divided portion is connected to the radiation shield such that the second curved portion is convex toward an opposite side to the radiation shield; An end portion of each of the divided second plates on the side of the divided portion is connected to the thermal insulating load supporting material, the second thermal expansion coefficient (2-2) of the second thermal deformation member is smaller than the first thermal expansion coefficient (1-2) of the radiation shield; The end portion on the side of the divided portion is thermally deformed with the thermal expansion coefficient of the second-2 in the same environment as that of the superconducting coil, thereby generating the second deformation amount.

3. The superconducting magnet device according to claim 2.

7. A plurality of the thermal insulating load supports are provided, Each of the insulating load bearing members comprises: are arranged in the vacuum vessel so as to surround the superconducting coil from a plurality of directions, supporting the superconducting coil via the thermal deformation cancellation mechanism at each of the arranged positions; The superconducting magnet device according to any one of claims 1 to 6.

8. a superconducting magnet device in which at least a superconducting coil is accommodated in a vacuum vessel in a state in which the superconducting coil is supported by a thermally insulated load support, the thermally insulated load support supports the superconducting coil via a thermal deformation canceling mechanism that generates a second deformation amount in a direction that cancels a first deformation amount applied from the superconducting coil to the thermally insulated load support by thermal deformation generated in the superconducting coil when the inside of the vacuum vessel is cooled to an extremely low temperature, the thermal deformation canceling mechanism including at least a thermal deformation member that is made of a material having a second thermal expansion coefficient determined based on a first thermal expansion coefficient of a material forming the superconducting coil and that generates the second deformation amount by thermally deforming in the same environment as the superconducting coil; a static magnetic field power supply for supplying power to the superconducting magnet device; a control unit that controls at least the power supply from the static magnetic field power supply when generating a magnetic resonance image of a subject imaged in a space of the static magnetic field generated by the superconducting magnet device; A magnetic resonance imaging apparatus comprising:

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